Bleaching compositions have long been in use in households for bleaching and cleaning fabrics. Liquid hypochlorite bleaches have been used most extensively. These hypochlorite bleaches are inexpensive, highly effective, easy to produce, and stable. The advent of modern synthetic dyes and their inclusion in fabrics has introduced a new dimension in bleaching requirements. Modern automatic laundering machines have also changed bleaching techniques and requirements.
The increasing complexity of modern fabrics and laundering equipment has brought forth a need for other types of bleaching compositions. To satisfy this need and to broaden and extend the utility of bleaches for household use, other bleach systems have been introduced in recent years.
Dry bleaching compositions based upon peracid chemical species are desirable new bleaching products. The peracid chemical compositions include one or more of the peroxyacid substituent: ##STR1##
The ##STR2## linkage provides a high oxidizing potential. This appears to be the basis for the bleaching ability of such compounds.
In bleach and detergent bleach formulations, it is desirable to combine these peracid compounds with surfactants, builders and fillers. There is a need for fillers, such as sodium sulfate, which are needed to bulk up the bleach product in order to provide easily measurable amounts of bleach product in usage.
However, in these bleach products there remains a need to include exothermic control agents to stabilize against violent decomposition of these peracids. Surprisingly, however, when hydrated magnesium sulfate/sodium sulfate is used as an exotherm control agent, the amount of water present must be rigorously controlled or non-exothermic decomposition of the peracid occurs givng poor product shelf stability.
It is also desirable to include an enzyme in household cleaning products for stain removal purposes. Exemplary enzymes are selected from the group of enzymes which can hydrolyze stains and which have been categorized by the International Union of Biochemists as hydrolases. Grouped within the hydrolases are proteases, amylases, lipases and cellulases.
However organic peracids, while active oxidizing agents are useful in fabric bleaching, also appear to affect enzyme stability since enzymes are somewhat sensitive proteins which have a tendency to denature or change their molecular structures in harsh environments. For this reason, enzymes may be denatured in an environment where there is a concentration of peracid bleaching species.
There is nothing in the prior art which discloses, teaches or suggests that it is crucial to control the amount of water present in the hydrated salt used as an exotherm control agent in a granular peracid composition in order to control peracid decomposition.
Additionally, nothing in the art discloses, teaches or suggests that control of the water in the exotherm control agent is crucial to maintain enzyme stability in peracid-containing compositions.
The present invention solves all of the above and other problems associated with diperacid bleaching compositions.